Acids & Bases

Question 1

What are the causal/ “maintenance” mechanisms of a renal metabolic alkalosis?

Answer 1

1. Volume contraction- causes proximal HCO3 reabsorption with sodium
2. Hypokalemia (from increased aldosterone activity) causes an increase in acid excretion

Question 2

Gitelman’s syndrome

Answer 2

Autosomal recessive condition, resembles action of a thiazide diuretic
Renal electrolyte wasting with metabolic alkalosis
may have osmotic diuresis from ions

Question 3

Bartter’s Syndrome

Answer 3

Resembles loop diuretic, causes decreased EABV and excretion of sodium, potassium, chloride
Usually picked up early in life

Question 4

Positive urine charge

Answer 4

This results from issues with ammonium secretion- not as much chlorine goes out so less negative charges in the urine

Question 5

Negative urine charge

Answer 5

This means that ammonium secretion is normal, and there is lots of chlorine in the urine so net negative

Question 6

RTA I

Answer 6

Alpha cell issue with ammonium secretion
Causes: secretory defect
clues: positive urine charge, high TTKG

Question 7

RTA II

Answer 7

PCT issue with bicarb reabsorption

clues: negative urine charge, high Fe HCO3

Question 8

RTA IV

Answer 8

Principal cell issue with ammonium secretion

causes: hyperkalemia causing defective ammoniagenesis or low NH3 availability
clues: positive urine charge, low TTKG

Question 9

What is required for H+ secretion in ammonium?

Answer 9

1. Proton pump
2. Luminal negative charge
3. NH3

Question 10

Where and how is H+ secreted?

Answer 10

1. Cortical collecting duct as:
   Sodiumphosphate
   Ammonium chloride

Question 11

Where is bicarb reabsorbed?

Answer 11

The PCT

Question 12

Salicylate poisoning

Answer 12

Acidemia but may have compensating respiratory alkalosis

May have hypokalemia

Question 13

Normal compensation for metabolic acidosis

Answer 13

1:1

Question 14

Normal compensation for metabolic alkalosis

Answer 14

10:7